Collagen is a fibrous protein comprised mostly of the white fiber found in the connective tissues of animals and man, especially in the skin, muscles and tendons. Hemostatic activity is an inherent property of collagen and is largely dependent on the basic helical structure of the collagen protein. When collagen comes into contact with blood, platelets aggregate on the collagen and release coagulation factors which, together with plasma factors, result in the formation of fibrin and finally in the formation of a clot. One of the advantages of collagen as a hemostat is that it is absorbed by the body due to enzymatic digestion and other body absorption processes.
It has also been found that local stoppage of bleeding and tissue bonding is enhanced with blood clotting factors such as thrombin. Cioca, in U.S. Pat. 4,515,637 which issued May 7, 1985, discloses a method of forming a collagen-thrombin hemostatic composition by forming a homogeneous aqueous admixture of collagen and thrombin at a basic pH and lyophilizing a collagen-thrombin admixture to form a stable collagen sponge having thrombin incorporated therein.
Collagen sponges, including those containing thrombin as disclosed by Cioca, are effective hemostats but have the disadvantage of not making intimate contact with a wound. Sponge hemostats have a planar structure, which prohibits intimate contact with the bleeding capillaries of a wound at the interior of an incised site. An alternative to collagen sponges are collagen- Powders or fibers such as the product sold as AVITENE brand, which is made of small collagen fibers that are effective for packing deep in the interior of a wound bed. Such powdered or fibrous products, however, are difficult to handle since the powder or fibers stick to wet gloves and form a gel thereon making application of the AVITENE to the wound site difficult.
It is therefore an object of the present invention to provide a collagen hemostat that can be packed intimately into a wound bed or site that is easy to handle and does not stick to wet gloves. Additionally, it is desirable that excess hemostat placed in the wound bed be easily removable from the wound after hemostasis is achieved.